Flight Report Fw 190/665
Nr. 2
Werk Flughafen 

Date: Flight Nr. Take-off: Landing: Duration: Pilot:
12.10.42 30 1030 1046 16' Bartsch

Condition: Production
Engine BMW 801 D II/25453
Tight engine cowl.
Split flaps with measuring system for the opening angle.
px and px Δ measuring equipment.

1.) Measurement of the stiffness of the split flap actuator with or without pre-load.
2.) Determination of the split flaps opening angle as a function of ram pressure.

1.) In order to determine the stiffness of the split flaps actuator, the opening force was determined, as a function of the opening angle. The outer edge of the rear split flap L and R (viewed in the direction of flight) was chosen as the point of attack for the force. The distance from the pivot point of the flap was ~ 85 mm. Force direction was always perpendicular to the flap pivot point. In the condition as delivered, the flap actuator was very soft (without pre-load) resulting in a flap opening angle of already ~ 8° at a 40 kg load. To modify this unacceptable condition for speed measurements, the actuator has been changed so that now the flaps remain just closed at P + 40 kg (Graph sheet 1).
2.) Graph sheet 2 shows the results obtained in flight. With a Va = 500 km/h the split flaps set up under 40 kg pre-load remain just closed, while the flaps left in the delivery condition already show 11,5° opening angle. At Va = 750 km/h also the pre-loaded flaps open up, namely to ~ 9°, this corresponds to a load of ~ 70 kg according to Graph 1. It is important to ensure that the split flaps remain closed at least up to the maximum level ram pressures (q = 1500).

The split flaps actuator already clatters after a short time of operation, the bolts of the small flap drive levers must then be strengthened and replaced. In addition, the foundation of the mounting on apparatus bay door is much too soft.

Wenzendorf, 13 October 1942


Flugbericht Fw 190/665 Nr. 2 (pdf)

Translation by Jörn Dietrich and Mike Williams

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